1. Field of the Invention
The present invention is to provide a cylinder lock in which a rotor is rotatably accommodated in a rotor case.
2. Related Art
Conventionally, in this type cylinder lock, tumblers are movably inserted into a plurality of tumbler insertion holes provided in the rotor, and when a key is not inserted into the keyhole, a lock condition holding portion of each tumbler is engaged with a lock groove in the rotor case, so that the rotor can be maintained in a lock condition.
According to the device described above, when the key is inserted into the keyhole, a protruding and cutout portion of the key is engaged with the lock condition release member of the tumbler. In the process of insertion of the key, each tumbler is pushed upward or downward along the protruding and cutout portion of the key. After the completion of key inserting operation, the protruding and cutout portion of the key is engaged with a predetermined lock condition release portion of the tumbler, and the tumbler is moved so that the lock condition holding portion can be released from the lock groove. Next, the key is operated so as to rotate the rotor.
In this connection, when an operator inserts the key into the keyhole, he is well aware of the rotational operation of the key to be conducted after the insertion of the key. Therefore, he tends to insert the key into the keyhole while a torque is applied to the key. However, in the conventional construction described above, when the key is inserted into the keyhole while a torque is applied to the key, the tumblers which are pushed upward or downward come into pressure contact with a side of the lock groove. Therefore, even after the key inserting operation has been completed, the tumblers can not be moved due to a frictional force generated between the tumblers and the side of the lock groove. For this reason, there is a possibility that the lock condition holding portion is not disengaged from the lock groove. When the lock condition holding portion is not disengaged from the lock groove, the next rotational operation of the key can not be smoothly performed.